1. Field of the Invention
The present invention provides a transmitter and a transmission circuit, and more particularly, a transmitter and a transmission circuit with the compensation of the equivalent inductance effect for improving the quality of the transmission signals.
2. Description of the Prior Art
In modern society, every kind of information, data, document, video file has been transformed into electrical signals. How to transmit electrical signals for information circulation more effectively has also become the target of the modern information industries. For instance, in the electronic system or network system, data exchange between different circuits, devices, and terminals are accomplished by buses or network transmission lines. Therefore, raising the efficiency of the signal transmission between circuits, maintaining the quality of the signal transmission, and lowering the power dissipation of the signal transmission contribute to the rises of the entire efficiency and the performance of the system.
Generally, when a transmission circuit transmits signals to a receiving circuit through connections (i.e. buses or network cables), the transmission circuit inputs the signals to the transmitter which transforms the input signals into output signals and then transmits them to the receiving circuit. However, as known by those skilled in the art, the quality of the signal transmission are affected by the natural characteristics of the connection (i.e. the connection length, the equivalent output impendence, and load of the connection) and the signal itself (i.e. the frequency, and the clock). For instance, the transmission circuit transmits a signal of the square waveform to the receiving circuit, but in fact, the waveform of the signal at the receiving circuit is changed from square into saw-tooth since the signal is weakened during the transmission process. Thus, the receiving circuit receives the signal different from the original one, causing the receiving circuit to misread the original signal.
In the prior art, to improve such bad transmission characteristics, two transmitters and a clock delay circuit are used in the transmission circuit. The waveform of the output signal is pre-emphasized so that the amplitudes at the rising edges and the falling edges of the waveform are strengthened and the distortion is reduced. However, there are disadvantages of the prior art. First, the prior art uses two transmitters to synthesize one emphasized output signal, which increases the power dissipation and the layout area. Second, the prior art also needs a clock delay circuit to properly synthesize the emphasized signal, and the clock delay circuit needs an external clock.
Additionally, the prior art also uses the current-mode logic(CML) transmitter. The kind of the transmitter adopts n-type MOS transistors, resistors, and inductors coupled to the resistors in series for emphasizing the waveform of the output signal. However, for realizing such transmitter, the coil structure of the inductor needs a great deal of layout area and the selection of the inductor is not so flexible, which is not convenient.